Stabilization of organic isocyanates with organic aldoximes



United States Patent 3 284,480 STABILIZATION OFbRGANIC ISOCYANATES WITH ORGANIC ALDOXHMES David T. Manning, South Charleston, W. Va, assignor to Union Carbide Corporation, a corporation of New York No Drawing. Filed May 9, 1963, Ser. No. 279,338 10 Claims. (Cl. 260-453) This invention relates to isocyana-te compositions, particularly an isocyanate composition stabilized from discoloration.

lsocy-anates are typically colorless liquids or solids which are found to discolor on storage. Discoloration of isocyanates deleter-iously affects their saleability typically because the color may be transferred to the product in which the isocyanate is employed. This is particularly so in the case of polyisocyanates used in resin manufacture.

It is herein described an agent which significantly retards discoloration of the isocyanate product thus allowing storage of the isocyanate for reasonable periods of time prior to use. These agents are particularly effective when employed in solution with the isocyanate.

The agents employed in this invention for retarding discoloration of organic isocyanates are aldoximes, that is, organic compounds bearing the CH:NOH group.

These aldoximes may be characterized by the formula:

wherein R may be groups such as alkyl, aryl, halo-alkyl, acylalkyl, aroylalkyl, acyloxyalkyl, aroyloxyalkyl, cycloalkyl, ara'lky l, cyanoa-lkyl, alkenyl, alkoxycarbonylalkytl, ary-loXycarbonyla-lkyl, and the like.

Illustrative alkyl groups include those of 1 to 12 carbon atoms, such as methyl, ethyl, n propyl, i-pro-py'l, n butyl, tbutyl, n-ipentyl, n-hexyil, n-octyl, n-nonyl, Z-n-propylhexyl, n-decyl, n-undecyl, n-dodecyl, and the like. The resulting aldoxirnes include aceta-ldoxime, .propio-na ldoxime, nbutyraldoxime, -i-butyraldoxime, pentanaildoxirne, 2,2-dirnethylpropionaldoxime, hexanaldoxime, hept-analdoxime, Z-ethylheptanald-oxime, 4-propylhexanaldoxime, 3,3,S-trirnethylhexanaldoxime, octanaldoxime, nonanaldoxime, decana'ldoxime, 3-n pro-pylhepta-na-ldoxirne, undec-analdoxime, dodecana-ldoxime, and the like.

Illustrative aryl groups include .phenyl, alpha-naphthyl, beta-naphthyl and phenanthryl. The corresponding al-doximes include benza'ldoxime, alph-a-naphthaldoxime, betanaphthaldoxime and phena-n-thraldoxime.

Illustrative haloalkyl groups include those of the formula:

wherein n is an integer of from 1 to 10, R, R, R and R" can be hydrogen or the alkyl groups described above; and X is halogen such as chlorine, bromine, fluorine, and the like. Examples of haloa-lkyl groups encompassed by Formula 11 include 3-chloropropyl, 4-fiuorobutyl, 5- bromopenty'l, 6-chlorohexyl, 7-fluoroheptyl, l2-ch lorod-odecyl, 3-chloro-l-methylpr-opyl, S-fl'uoro-l-propylpentyl, 7-bro-mo-lbuty-lheptyl, 9-chl-oro-1-ethylnonyl, IZ-chloro- 1-i-propyld-odecyl, 3-ch-lor'o-1,l diethylpropyl, 5-chl0ro- 1-t-butyl-1 methyilpentyl, 7-brorno-l-ethyl-l-propy-lheptyl, 9-fluoro-1,1-dipropylnonyl, and 12-bromo-l-hexyl-1-methyldodecyl, 4 chloro-4-methylhexyl, S-ethyl-S-fiuoro-6- methylheiptyll and 8-bromo-1D-t-butylundecyl, and the like. The resulting aldoximes include 4-chlorobutyraldoxime, S-fluoropentanaldoxime, 6-bromohexanaldoxime, 7-chloroheptanaldoxime, S-fluorooctanaldoxime, 13-chlorotridecanaldoxirne, 4-ch1oro-2-methylbutyraldoxime, 6-fluoro- Patented Nov. 8, 1966 wherein n is an integer of from 1 to 10, R can be a'lky'l, cyoloalkyl, haloialkyl, aryl or aralkyl, and R R R and R can be hydrogen or R Examples of groups encompassed by Formula 111 include 3-(4chlorobutyryl)propyll, 5-acetyil entyl, 7-benzoylhe-ptyl, 9-phenylacetylnonyl, 11- propionylundecyl, 1-ethyl-1-methyl 3 acetylpropyl, 5- benzoyil l-butylpentyl, 7-i-butyryl-l-methytl-l propyilheptyil, 9-(4-ch lorovalery l) 1,1 dimethyilnonyd, l-buty-l-lrn-ethyl-12-phenylacetyldodecyl, 4-acetyl-4-ethyl-4-methylbutyl, 6-phenyl-6-propionylhexyl, 9-benZoyl9,9-dimethylnonyl, 1l-methyl-l1-phenytlacetylundecanyl, ,and the like. The resulting aldoximes include 4-(4-chlorobutyryl)butyraldoxime, 6 acetylhexanaldoxime, 8-benzoyiloctana1doX- irne 1O- henylacetyldecanaldoxime, 12-propionyldodecanaldoxirne, 2-ethyl-2-methyl-4-acety lbutyraldoxime, 6-benzoyl-Z-butylhexanaldox'ime, 8-i-butyryl-2-methyl-2-propyloctanaldoxime, 10 (4-chlorovaleryl) -2,2-dimethyldecanaldoxime, 2-butyl-2-methyl-13aphenylacetyltridecanaldoxime, S-acetyl 5 -methylheptanaldoxime, 7 phenyl-7-propi-onylheptanaldoxime, 10 benzoyl-IO-methylundecanaldoxime, 1Z-phenylacetyltridecanaldoxime, and the like.

Illustrative acyloxyalkyl and aroyloxyalkyl groups include those of the formula:

(IV) R1 R ("J-o(0Hi)..-( 3

wherein a is an integer of from 2 to 11, R is the same as R described above, and R and R can be hydrogen or R Examples of groups encompassed by Formula IV include 3-propionoxyproipyl, 5-benzoyloxypentyl, 7-b-utyroxyhepty l, and 12-acetoxydodecyl, 4 propionoXy-1-methyl-lapropylbutyl, 6-benzoyloxy-l-ethylhexyl, S-butyroxyl-b-uty l-l-methyloctytl, ll-acetoxy l benzy l 1 ethylundecyl, and the like. The aldoximes include 4-propionoxybutyraldoxime, 6-benzoyloxyhexanaldoxime, Sabutyr- 'OXYOCtHHZUldOXlIIlB, and 13-acetoxytridecan-aldoxime, 5'- propionoxy-2-methyl-2-propylpenta'naldoxiine, 7 benzoyloXy-2-etihylheptanaldoxime, 9-bu'tyroXy-2-butyl-2-methylnonanaldoxime, 12 acetoxy-Z-benzyl-Z-ethyldodecanaldoXime, and the like.

The aforementioned cycloalkyl groups are preferably those containing from 5 to 7 carbon atoms in the ring, such as cyclopentyl, cyclohexyl and cycloheptyl. The resulting aldoximes include cyclopentanecarboxaldoxime, cyclohexanecarboxaldoxime, cycloheptanecarboxaldoxime, and the like.

The aralkyl group may be one of a variety of radicals encompassed by the term aralkyl, and desirably, the group is represented by those encompassed by the formula (v) A (01-Ii b wherein b is an integer of from 1 to 10, and AR can be an aryl group such as phenyl, alpha-naphthyl, beta-naphthyl, phenanthryl, an-thryl, and the like. Specific aralkyl groups encompassed by Formula V include: benzyl, Z-phenylethyl, 6-alpha-naphthylhexyl, S-beta-naphthyloctyl, IO-phenyl- 3 decyl, and the like. The resulting aldoximes include benzaldoxime, 3-phenylpropanaldoxime, 7-alpha-naphthylheptanaldoxime, 9 beta naphthylnonanaldoxime, l1- phenylundecanaldoxime, and the like.

The cyanoalkyl groups referred to previously are typically those encompassed by the formula wherein n is as described above, and R R R and R can be hydrogen or groups such as alkyl, cycloalkyl, haloalkyl, aryl or aralkyl. Illustrations of groups encompassed by Formula VI include 3-cyanopropyl, S-cyanopentyl, 7- cyanoheptyl, 9-cyanononyl, ll-cyanoundecyl, 12-cyanododecyl, 3-cyano-1-ethyl-l-methylpropyl, 6-cyano-1-butylhexyl, 9-cyano-l-butyl-l-methylnonyl and 11 cyano 1- ethyl-l-hexylundecyl, 3-cyano-3-ethyl-3-methylpropyl, 5- cyano-5metl1ylpentyl, 7-cyano-7-butyl-7-cyclohexylheptyl, 9-cyano-9,9-diethylnonyl, and the like. Aldoximes containing groups illustrated by Formula VI include e.g., 4- cyanobutyraldoxime, 6 cyanohexanaldoxime, 8 cyanooctanaldoxime, IO-cyanodecanaldoxime, 12-cyanododecanaldoxime, 13-cyanotridecanaldoxime, 4-cyano-2-ethyl-2- methylbutyraldoxime, 7-cyano-2butylheptanaldoxime, l0- cyano-Z-butyl-Z-methyldecanaldoxime, 12-cyano-2 ethyl- 2-hexyldodecanaldoxime, 4-cyano-4-methylhexanaldoxime, 6-cyanoheptanaldoxime, 8-cyano-8 cyclohexyldodecanaldoxime, lO-cyano-lO-ethylodecanaldoxime, and the like.

The alkenyl groups referred to previously typically contain from 2 to about 10 carbon atoms and from 1 to 2 eth yleHiC moieties per group. Illustrative 'alkenyl groups include vinyl, propenyl, allyl, l-methylvinyl, l-cyclohexylvinyl, Z-methylpropenyl, 1-methyl-2-phenylvinyl, 2-pheny1vinyl, 1-hexenyl, l,3pentadienyl, 3-cyclohexenyl, and the like. The resulting alkenyl aldoxime may be e.g., acrolein oxime, crotonaldoxime, vinylacetaldoxime, methacrolein oxime, cyclohexylacrolein oxime, 3 methylcrotonaldoxime, 2- methylcinnamaldoxime, cinnamaldoxime, 2 heptenaldoxime, sorbaldoxime, 3-cyclohexencarboxaldoxime, and the like.

The alkoxycarbonylalkyl groups referred to above, are typically characterized by the formula:

(VII) R oi :-(oH2 wherein a is an integer of from 3 to 12 and R is the same as described for R". Formula VII characterizes such groups as 3-ethoxycarbonylheptyl, S-benzyloxycarbonylpentyl, 7-cyclohexyloxycarbonylheptyl, 12-propoxycarbonyldodecyl, and the like. Aldoximes bearing the groups characterized by Formula VII include e.g., 4-ethoxycarbonylbutyraldoxime, 6 benzyloxycarbonylhexanaldoxime, 8-cyclohexyloxycarbonyloctanaldoxime, 13 propoxycarbonyltridecanaldoxime, and the like.

The isocyanates which may be treated to retard discoloration are organic monoand polyisocyanates, such as aliphatic, cycloaliphatic and aromatic mono-, di-, triand/ or other polyisocyanates which tend to discolor under conditions of moisture and temperature typically associated with industrial storage procedures. Illustrative of organic isocyanates which are beneficially stabilized from discoloration include the following:

tolylene-2,4- and 2,6-diisocyanate, 4,4-methylenedi-o-tolylisocyanate, 2,4,4'-triisocyanatodiphenylether, toluene-2,4,6-triisocyanate, 1-methoxy-2,4,6-triisocyanatobenzene, m-phenylenediisocyanate, 4-chloro-m-phenylenediisocyanate, ,4-bipheny1d is cyanate;

1,5-naphthalenediisocyanate, 1,4-tetramethylenediisocyanate, 1,6 -hexamethylenediisocyanate, 1,10-decamethylenediisocyanate, 1,4-cyclohexanediisocyanate, 1,Z-ethylenediisocyanate, 4,4--methylenediphenylisocyanate, bis(4-isocyanatocyclohexyl)methane, stilbene diisocyanates,

dixylylmethane diisocyanates,

2,2-bis p-isocyanatophenyl propane, diphenylmethane tetr-aisocyanate, trimethylbenzene triisocyanates, phenyltolylmethane t-riisocyanates, ditolylmethane triisocyanates, triphenylmethane triisocyanates, 3,3'-dimethyldiphenylene-4,4-diisocyanate, 3,3'-dimethoxyldiphenylene-4,4'-diisocyanate, diphenyl triisocyanates and isomers of his (p,p'-isocy-anatophenyl) cyclohexane.

The aforementioned color retardation agents (color stabilizing agents) should be capable of dissolution in the particular isocyanate to be stabilized regardless of whether the isocyanate is a liquid at ambient temperature or must be warmed to transform it to the liquid state. It is apparent that the agent should be stable at the temperature of the isocyanate at the time of incorporation and incorporation be effected at a temperature below that of decomposition or of any undesirable reaction of the isocyanate with itself or the agent. The agent, or mixtures of the agents, should be employed in the isocyanate in any amount sulficient to retard discoloration. Usually that amount falls between 0.005 and 5 percent by weight of the isocyanate. Preferably, the agent is employed in amounts from about 0.01 to 1.0 percent by Weight of isocyanate. In general, this invention is directed to employing an amount of the agent sufficient to retard discoloration of the isocyanate.

The following serves to specifically illustrate operation of this invention, however, it is not intended to limit the scope of this invention.

Example I A dry 8-ounce glass bottle is purged with dry nitrogen and charged with a mixture of 130 grams of substantially colorless, pure, freshly-distilled tolylene diisocyanate weight percent 2,4-tolylene diisocyanate and 20 weight percent 2,6-tolylene diisocyanate) and 0.13 gram of acetaldoxime. The resulting composition is blanketed under dry nitrogen and the bottle is securely sealed by wrapping its stopper with tape. A similar sample is prepared, but without the added acetaldoxime, for use as a blank.

Both the blank and the acetaldoxime test samples are stored in the dark at room temperature, about 25 C. Examination after storage for four days reveals the development of a definite yellow color in the blank while, the sample containing acetaldoxirne remains unchanged. After 14 days, the sample containing acetaldoxime exhibits significantly less coloring than the blank sample.

Example II When the procedure of Example I is repeated except that 0.13 gram of benzaldoxime is substituted for the acetaldoxime, the benzaldoxime-containing sample exhibits significantly less yellowing than the blank sample after a 14-day storage period.

Example lIl When the procedure of Example I is repeated except that 0.13 gram of n-heptaldoxirne is substituted for the acetaldoxime, the n-heptaldoxime-containing sample exhibits significantly less yellowing than the blank sample after an 8-day storage period.

The same results are obtained when n-butyraldoxime and iso-butyraldoxirne are employed.

Example IV group to retard discoloration of the organic isocyanate where R and R are hydrogen or a 1-12 carbon atom alkyl group.

2. A solution of organic isocyanate and 0.005 to 5 percent by weight of the isocyanate of organic compound bearing a group where R and R are hydrogen or a 1-12 carbon atom alkyl group.

3. A solution of organic isocyanate and 0.01 to 1.0 percent by weight of the isocyanate of organic compound bearing a R1 -(|]-CH=NOH group where R and R are hydrogen or a 1-12 carbon atom alkyl group.

4. The solution of claim 1 wherein the organic diisocyanate is an organic polyisocyanate.

5. A solution of tolylene diisocyanate and a sufiicient amount of acetaldoxime to retard discoloration of said diisocyanate.

6. A solution of tolylene diisocyanate and a sufiicient amount of benzaldoxime to retard discoloration of said diisocyanate.

7. A solution of tolylene diisocyanate and a sufficient amount of n-heptaldoxime to retard discoloration of said diisocyanate.

8. A solution of tolylene diisocyanate and a sufficient amount of n-butyraldoxime to retard discoloration of said diisocyanate.

9. A solution of tolylene diisocyanate and a suflicient amount of iso-butyraldoxime to retard discoloration of said diisocyanate.

10. A solution of tolylene diisocyanate and a sufiicient amount of 2,4-hexadienaldoxime to retard discoloration of said diisocyanate.

References Cited by the Examiner UNITED STATES PATENTS 3,107,232 10/1963 Matlack 252-400 X CHARLES B. PARKER, Primary Examiner.

JOSEPH P. BRUST, D. R. MANANAND,

Assistant Examiners. 

1. A SOLUTION OF ORGANIC ISOCYANATE AND A SUFFICIENT AMOUNT OF ORGANIC COMPOUND BEARING A -C(-R1)(-R2)-CH=N-OH GROUP TO RETARD DISCOLORATION OF THE ORGANIC ISOCYANATE WHERE R1 AND R2 ARE HYDROGEN OR A 1-12 CARBON ATOM ALKYL GROUP. 